The fields of salvaging and remanufacturing machine components have greatly expanded in recent years. Many parts which in the past would have been scrapped are now returned to service. Giving machine components further service life not only conserves resources, but also can create new revenue sources for manufacturers, machinists and mechanics. One challenge to successfully remanufacturing many parts is returning them to original specifications. In other words, it is typically desirable to remanufacture a part such that dimensions, operation, reliability, etc. are as close as practicable to those of a new part. In some instances, remanufactured parts may even be superior to new parts, as inspection and testing of individual remanufactured parts can often be more exacting than conventional analysis of many mass-produced new parts.
A unique set of challenges are associated with remanufacturing certain machine components used in hydraulic systems. Many modern hydraulic systems, such as internal combustion engine fuel systems, utilize rapidly moving valve components to control the timing, rate and other characteristics of fluid flow. Over the course of a fuel injector's service life, for example, its valve components may be required to actuate millions or even billions of times. The physical demands placed on such components will be readily apparent. When a fuel injector is to be remanufactured, certain functional surfaces of components of the fuel injector can be worn or otherwise damaged to the point that injector performance is compromised.
Valve seats within fuel injector valve bodies are one example of a functional surface which can be damaged from use, and ultimately affect fuel injector performance. Over time, a valve member striking a valve seat can deform the valve seat. Fluid flowing at relatively high pressure and relatively rapid fluid pressure changes can erode the valve seat and/or cause cavitation. U.S. Pat. No. 6,339,887 B1 to Straub et al. (“Straub”) proposes one strategy for refurbishing a valve seat in a fuel injector assembly. In Straub, a tool is moved along a known reference axis to lap the valve seat. Lapping of the valve seat can presumably remove wear so that the associated component can be successfully returned to service. While Straub's approach might provide successful valve seat refurbishing in some instances, or for certain valve types, Straub and other known refurbishing strategies have various drawbacks. Many valve seats, and in particular the type used in fuel injectors, are typically made from hardened materials. It is common, however, for only the valve seat and material in the vicinity of the valve seat to be hardened. Apart from the hardened material in the vicinity of the valve seat, the component having the valve seat is often made from relatively softer material. This softer material may be unsuitable for use as a valve seat in a fuel injector's typical service environment. Thus, regrinding of the valve seat can remove the relatively hard material and expose softer material, rendering the fuel injector unsuitable for use. This can be especially problematic where hardened material has already been removed in a prior round of remanufacturing. Moreover, in some instances valve seat damage may be severe enough that regrinding cannot cure the problem without removing all of the hardened material.